I've been mandated to find out what IBM Cognos does, and I cannot find useful information on the subject apart what I can read from the IBM Website and Wikipedia.
What I'm after is some concrete examples of what Cognos can do for businesses and organisations that intend to use it.
Financial Performance Management I have no idea about but we use BI 8.4/10.1 quite a bit. The Cognos product line is actually quite large and we only really use the baseline BI stuff with Framework Manager but I'll try and help you out, based on how we use it.
Think of BI itself as an application that lets you view your data in many different ways. Now so far, it's no different to Jasper Reports or BIRT (which, despite its name, appears to provide very little BI stuff).
It does this by modelling the data (models are created with Framework Manager hence why we use it over and above the standard reporting interface) to translate raw data into business data and also relational to dimensional data if your database isn't already dimensional.
It's this business view of the data combined with the dimensionality which allows really neat manipulation within Cognos BI.
You can create reports in a truly multi-dimensional way, aggregating data in various ways across things like dates, products, geographical regions, stores, divisions and so on (depending on your dimensional setup).
All of the reports are really dynamic in that you can collapse or expand individual dimensions at will so, if for example you want to drill down on a poorly-performing state to see which individual stores in that state are causing problems, it's a simple click on an icon.
No re-querying of the data, everything just happens in very quick time. And the charts and data that can be produced are very nice.
And, on top of that, Cognos BI comes with an inbuilt query studio and report studio which allow the creation of ad-hoc reports in the exact same interface the user sees when running standard reports. No more of the Eclipse-Designer/Web-App separation that we had to endure with BIRT.
Sorry if this sounds evangelistic but we're transitioning from BIRT to Cognos BI, and the difference is substantial.
Now you may not find a lot of information outside of the IBM website, although we did find a couple of dedicated sites when we first started examining the transition. Unfortunately, I don't have them available any more since the IBM information is more than adequate.
We also make a lot of use of the IBM developerWorks forums (we use Tivoli Common Reporting which ships with the Cognos runtimes) and the microsite as well. As well as the forums, there's a whole section of developerWorks dedicated to Cognos.